[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 212341
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE 21 SEP 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC OCEAN TO THE AFRICAN
COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...
RADAR...AND METEOROLOGICAL ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

HURRICANE JEANNE IS CENTERED NEAR 27.3N 68.8W OR ABOUT 515
MILES... 830 KM...EAST OF GREAT ABACO ISLAND AT 21/2100 UTC.
JEANNE IS MOVING SOUTHEAST 5 KT. MAXIMUM SUSTAINED WIND SPEED IS
80 KT WITH GUSTS TO 100 KT AND THE ESTIMATED MINIMUM CENTRAL
PRESSURE IS 972 MB. SEE LATEST NHC PUBLIC ADVISORY OR NHC
FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/WTNT31 KNHC
OR MIATCMAT1/ WTNT21 KNHC FOR MORE DETAILS. THE OVERALL
CONVECTIVE STRUCTURE AND SATELLITE APPEARANCE HAS CHANGED LITTLE
OVER THE LAST SEVERAL HOURS.  THE STRONGEST CONVECTION CONTINUES
TO BE FOCUSED OVER THE W SEMICIRCLE WITH NUMEROUS STRONG
ACTIVITY WITHIN 100 NM OF THE CENTER.  CONVECTION REMAINS WEAK
OVER THE E SEMICIRCLE WITH SCATTERED MODERATE ACTIVITY WITHIN
120 NM OF CENTER.

HURRICANE KARL CENTERED NEAR 22.9N 48.6W OR ABOUT 990
MILES...1595 KM...EAST-NORTHEAST OF THE NORTHERN LEEWARD ISLANDS
AT 21/2100 UTC. KARL IS MOVING NNW AT 14 KT. MAXIMUM SUSTAINED
WIND SPEED 105 KT WITH GUSTS TO 130 KT AND THE ESTIMATED MINIMUM
CENTRAL PRESSURE 948 MB. SEE LATEST NHC FORECAST/ ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. KARL
HAS BEEN EXPERIENCING SWLY SHEAR DURING THE DAY AND THE
SATELLITE SIGNATURE HAS BECOME PROGRESSIVELY RAGGED.  THE EYE IS
NO LONGER VISIBLE IN IR IMAGERY AND THE CONVECTIVE PATTERN IS
MUCH LESS SYMMETRIC ABOUT THE CENTER.  THE STRONGEST CONVECTION
IS FOCUSED OVER THE S SEMICIRCLE WITH NUMEROUS STRONG ACTIVITY
WITHIN 100-120 NM RADIUS OF THE CENTER.  NUMEROUS MODERATE
CONVECTION WITHIN 100 NM OF CENTER OVER THE N SEMICIRCLE.
SCATTERED MODERATE CONVECTION IS ELSEWHERE OVER THE N SEMICIRCLE
WITHIN  100-300 NM OF THE CENTER.

TROPICAL STORM LISA IS CENTERED NEAR 14.4N 40.3W OR ABOUT 1090
MILES...1760 KM...WEST OF THE CAPE VERDE ISLANDS AT 21/2100 UTC.
LISA IS MOVING WNW AT 7 KT. MAXIMUM SUSTAINED WIND SPEED IS 60
KT WITH GUSTS TO 75 KT AND THE ESTIMATED MINIMUM CENTRAL
PRESSURE 990 MB. SEE LATEST NHC FORECAST/ADVISORY UNDER
AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
SATELLITE IMAGERY INDICATES THAT THERE HAS BEEN LITTLE CHANGE
DURING THE LAST 6 HOURS.  LISA IS MAINTAIN A SMALL YET WELL
DEFINED CDO FEATURE WITH ASSOCIATED NUMEROUS STRONG CONVECTION
ONLY COVERING A SMALL AREA WITHIN 30-40 NM RADIUS OF THE CENTER.

TROPICAL WAVE LOCATED APPROXIMATELY 500-550 NM WEST OF THE
SOUTHERNMOST CAPE VERDE ISLAND ALONG 34W SOUTH OF 15N MOVING
WEST 15 KT. A 1010 MB LOW IS CENTERED ALONG THE WAVE NEAR 11N.
WHILE CONVECTION ASSOCIATED WITH THIS SYSTEM HAS INCREASED IN
INTENSITY AND COVERAGE DURING THE LAST SEVERAL HOURS...THE
ORGANIZATION OF THE SYSTEM APPEARS UNCHANGED.  CURRENTLY...
SCATTERED STRONG CONVECTION FROM 8N-13N BETWEEN 31W-36W.
NONETHELESS...CONDITIONS REMAIN FAVORABLE FOR DEVELOPMENT AND A
TROPICAL CYCLONE COULD FORM TONIGHT OR WEDNESDAY.

...TROPICAL WAVES...

SEE SPECIAL FEATURES FOR TROPICAL WAVE ALONG 34W.

...ITCZ...

ITCZ EXTENDS ALONG 11N10W 5N22W 12N30W...DISRUPTED BY T.S. LISA
AND HURRICANE KARL BETWEEN 30W AND 50W...13N50W 6N70W 6N80W.
ASIDE FROM CONVECTION WITH TROPICAL WAVE ALONG 34W...AREA OF
SCATTERED STRONG CONVECTION MOVING OFF THE COAST OF AFRICA FROM
5N-13N BETWEEN 1W-16W.

...DISCUSSION...

GULF OF MEXICO...
MID/UPPER LEVEL TROUGH WHICH EXTENDED FROM THE W ATLC OVER
FLORIDA INTO THE GLFMEX YESTERDAY HAS SPLIT FORMING A LARGE
CUTOFF LOW OVER THE W TWO-THIRDS OF THE GLFMEX.  MULTIPLE
CIRCULATIONS ARE OBSERVED WITHIN THE LARGE GYRE WITH THE MOST
NOTABLE BEING ALONG THE COAST OF MEXICO NEAR TAMPICO.  AS A
RESULT OF THE TROUGH BECOMING CUTOFF...THE UPPER FLOW IS NOW
MORE DIVERGENT SUPPORTING WIDELY SCATTERED SHOWERS/THUNDERSTORMS
N OF 25N.  LOW LEVEL MOISTURE ASSOCIATED WITH THE REMNANTS OF
IVAN PUSHED ACROSS CENTRAL FLORIDA TODAY WITH ASSOCIATED
ACTIVITY IS NOW OVER THE E GLFMEX FROM 24N-27N E OF 88W TO THE
COAST OF FLORIDA.  THE UPPER PATTERN IS EXPECTED TO REMAIN
UNCHANGED THROUGH THE NEXT 36-48 HOURS KEEPING CLOUDINESS AND
SHOWERS/THUNDERSTORMS ACROSS THE N GLFMEX.  THE BULK OF THIS
ACTIVITY SHOULD BE FOCUSED ALONG THE N GULF COAST FROM MOBILE
BAY WESTWARD TO E TEXAS.

CARIBBEAN SEA...
LARGE MID/UPPER LEVEL HIGH IS CENTERED NEAR JAMAICA WITH
ASSOCIATED ANTICYCLONIC FLOW COVERING THE ENTIRE AREA INCLUDING
N PORTIONS OF S AMERICA. DRY AIR IN THE MIDDLE TO UPPER LEVELS
CONTINUES TO MARCH WESTWARD ACROSS THE CENTRAL AND EASTERN
CARIBBEAN SEA.  CONVECTION IS PRIMARILY FOCUSED OVER CENTRAL
AMERICA AND THE YUCATAN PENINSULA.  SCATTERED MODERATE
CONVECTION IS ALSO OBSERVED OVER HISPANIOLA...JAMAICA...AND THE
N COAST OF CUBA.

SUBTROPICAL ATLANTIC...
STRONG MID/UPPER LEVEL TROUGH N OF THE AREA EXTENDS SWD OVER THE
W ATLC TO 30N BETWEEN 45W-70W. ATTENDANT COLD FRONT ENTERS AREA
NEAR 32N52 WHERE IT PULLS UP STATIONARY AROUND THE N SIDE OF
HURRICANE JEANNE ALONG 30N THEN EXTENDING SW AND DISSIPATING
INTO THE N BAHAMAS.  MOISTURE FROM JEANNE CONTINUES TO STREAM
NEWD ALONG AND AHEAD OF THE SURFACE FRONTAL BOUNDARY PRODUCING
CLOUDINESS AND WIDELY SCATTERED SHOWERS/THUNDERSTORMS N OF 26N
BETWEEN 55W-65W.  ADDITIONALLY...STRONG SURFACE HIGH PRESSURE
MOVING INTO THE W ATLC BEHIND THE FRONTAL BOUNDARY IS PRODUCING
A LARGE AREA OF STRONG NE FLOW FROM BERMUDA WESTWARD TO THE SE
UNITED STATES COAST. OVER THE CENTRAL ATLANTIC...MIDDLE TO UPPER
LEVEL RIDGE EXTENDS OUT OF THE CARIBBEAN OVER HISPANIOLA NEWD IN
BETWEEN HURRICANE JEANNE AND HURRICANE KARL TO BEYOND 32N55W.
ASIDE FROM CONVECTION ASSOCIATED WITH KARL AND JEANNE...MODERATE
SUBSIDENCE AND DRY AIR PREVAILS PRODUCING TRANQUIL WEATHER
BETWEEN THE TWO HURRICANES.  FURTHER E...A HIGH AMPLITUDE
MID/UPPER LEVEL RIDGE E OF KARL EXTENDS NWD ALONG 42W COVERING
THE AREA WITH ANTICYCLONIC TO 30W. MIDDLE TO UPPER LEVEL TROUGH
OVER THE FAR E ATLANTIC EXTENDS FROM THE CANARY ISLANDS SWD TO
JUST W OF THE CAPE VERDE ISLANDS.  MODERATE SUBSIDENCE
ACCOMPANIES THE TROUGH PREVAILING E OF 30W. AT THE
SURFACE...SUBTROPICAL RIDGE EXTENDS FROM THE AZORES SW ALONG
30N30W TO 30N45W WHERE IT BECOMES DISRUPTED TO THE WEST BY
HURRICANE KARL AND JEANNE.

TROPICAL ATLANTIC...
WEAK MID/UPPER LEVEL RIDGING EXTENDS E/W ACROSS THE AREA ALONG
20N BUT REMAINS DISRUPTED IN THE VICINITY OF HURRICANE KARL AND
TROPICAL STORM LISA.  DEEP LAYERED ELY FLOW S OF THE RIDGE
EXTENDS ACROSS THE TROPICAL ATLC W OF 35W. FURTHER E...
MID-LATITUDE TROUGH OVER THE FAR E ATLC DIPS INTO THE TROPICAL E
ATLC W OF THE CAPE VERDE ISLANDS.

$$
RHOME


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